1. Field of the Invention
The present invention relates to a recording head that discharges a liquid, more particularly ink as a recording liquid used to perform recording in a recording medium in the form of droplets. The present invention also relates to a method of producing the liquid-ejecting recording head.
2. Description of the Related Art
An existing liquid-ejecting recording head and a configuration of major components of the liquid-ejecting recording head will be described by referring to FIGS. 10A and 10B. FIG. 10A is a perspective view of the liquid-ejecting recording head, and FIG. 10B is an exploded perspective view illustrating the configuration of the major components of the liquid-ejecting recording head. In FIGS. 10A and 10B, the liquid-ejecting recording head includes a recording element substrate 200 that discharges a liquid (ink) and an electrical wiring member 300 that provides electrical connection between the recording element substrate 200 and a recording apparatus and is formed of a flexible material. In addition, the liquid-ejecting recording head includes a tank case 100, to which components such as the recording element substrate 200 and the electrical wiring member 300 are fixed. The tank case 100 holds the ink therein.
In general, to mount the recording element substrate 200 in the electrical wiring member 300, gold-plated bumps are provided on the recording element substrate 200, and then a plurality of leads provided in the electrical wiring member 300 and the plated bumps are electrically joined together in the inner lead bonding (ILB) process. The recording element substrate 200 having been joined to the electrical wiring member 300 in the ILB process is then joined to the tank case 100 by adhesion. After that, an area surrounding the recording element substrate 200 is sealed with a first sealant 400 (hereinafter also referred to as boundary sealing). In addition, since there is a possibility that ink droplets or the like will adhere to an exposed part of electrical connection portions having undergone the ILB process if such an exposed part exists, the electrical connection portions are sealed by coating the electrical connection portions with a second sealant 500 such as an epoxy polymer that has a sealing ability (hereinafter also referred to as ILB sealing). Thus, the first sealant 400 and the second sealant 500 are respectively applied to the area surrounding the recording element substrate 200 and the electrical connection portions including the plated bumps and the leads. Then, the resultant structure is thermally cured and mounted in the liquid-ejecting recording head.
FIGS. 11A to 11C are plan views illustrating a schematic configuration of the major components of the liquid-ejecting recording head. Each of FIGS. 11A, 11B, and 11C illustrates a step in a manufacturing process of the liquid-ejecting recording head. FIG. 11A illustrates the state in which the recording element substrate 200 and the electrical wiring member 300, which have undergone the ILB process, are mounted in the tank case 100. FIG. 11B is a schematic plan view illustrating the state in which the first sealant 400 is applied to the area surrounding the recording element substrate 200 that is mounted in the tank case 100. FIG. 11C illustrates the state in which the second sealant 500 is applied to the electrical connection portions including the gold-plated bumps and the leads. Here, a material generally selected for the first sealant 400 used to seal the area surrounding the recording element substrate 200 has high flowability, and also has low tendency to apply stress due to curing shrinkage or the like to the recording element substrate 200 after the material has been cured. On the other hand, a material of the second sealant 500 used for the ILB sealing is selected by considering durability under use with a wiper blade or the like of a recording apparatus. Normally dispensing is performed so as to supply a desired amount of a sealant to a predetermined position using a three-axis robot having X, Y, and Z axes, a dispenser, syringes, needles and the like.
Boundary sealing as described above is performed as illustrated in FIG. 12. A dispensing end of the needle attached to the syringe in which the first sealant 400 is contained is positioned at A, which exists in a gap between the recording element substrate 200 facing a depression in a supporting member and the electrical wiring member 300. Then, the dispensing end of the needle is moved in a longitudinal direction (from A to A′ in FIG. 12) of the recording element substrate 200 while ejecting the first sealant 400 from the needle. Likewise, the dispensing end of the needle is moved from B′ to B to apply the first sealant 400. Since the first sealant 400 used has a comparatively good flowing property, it flows to an area below leads 301. Thus, boundary sealing is performed. Then, the second sealant 500 is applied on the leads 301 and the first sealant 400. The first sealant 400 and second sealant 500 are thermally cured. A liquid-ejecting recording head for which such sealing is performed is described in Japanese Patent No. 3592172.
In recent years, there has been a demand for recording apparatuses having a decreased size in the market. Decreasing the size of a liquid-ejecting recording head by narrowing the width of a tank case is effective in meeting such a demand. As the width of the tank case has been reduced in such an attempt to reduce the size of a liquid-ejecting recording head, the distance between a recording element substrate and an electrical wiring member has accordingly been reduced. Therefore, application of a sealant has become difficult. In particular, in a case where the sealant is applied using a needle as described above, application of the sealant becomes difficult since the dispensing end of the needle cannot move into a gap between the recording element substrate and the electrical wiring member.